- What is Western Disturbance:
- It is an extra tropical storm that originates in the Mediterranean region and brings heavy winter rains to the Indian subcontinent’s northwestern regions.
- The westerlies drive a non-monsoonal precipitation pattern.
- Extratropical storms are a global phenomena that carry moisture in the high atmosphere, as opposed to their tropical counterparts, which carry moisture in the lower atmosphere.
- When a storm system hits the Himalayas, moisture is sometimes released as rain on the Indian subcontinent.
- How Western Disturbances are caused:
- Western Disturbance is caused by extratropical cyclones that form in the Mediterranean Sea.
- A high-pressure area forms over Ukraine and the surrounding region, allowing frigid air from the Polar Regions to enter an area of somewhat warmer air with significant moisture.
- This encourages the formation of an eastward-moving extratropical depression by creating favourable circumstances for cyclogenesis in the upper atmosphere.
- They make their way across the Middle East, passing via Iran, Afghanistan, and Pakistan on their way to the Indian subcontinent.
- Impact:
- Plays a key role in bringing moderate to heavy rain to low-lying portions of the Indian Subcontinent, as well as heavy snow to mountainous areas.
- Cloudy skies, warmer night-time temperatures, and unexpected rain are frequently linked with this disturbance.
- This precipitation is critical in agriculture, particularly for Rabi crops.
- Wheat is one of the most significant crops that contributes to India’s food security.
- Crop damage, landslides, floods, and avalanches can all be caused by excessive precipitation caused by this disturbance.
- It brings cold waves and dense fog to the Indo-Gangetic plains on occasion.
- Until another western disturbance disrupts the situation, these circumstances will remain stable.
- A transient advancement of monsoon current develops across the region when western disturbances sweep across northwest India before to the onset of monsoon.
- Source The Hindu